\version "2.18.0"

up = \drummode {
% Stems Up notes go here
  <hh bd>8[ hh] <hh sn>[ hh] <hh bd>[ <hh bd>] <hh sn>[ hh]
}

down = \drummode {
% Stems Down notes go here

}

\score
{
  <<
    \new DrumStaff
    <<
      \new DrumVoice { \voiceOne \up }
      \new DrumVoice { \voiceTwo \down }
    >>
  >>
}